Where can I find very technical data about flash output (colour spectrum/wavelengths)

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I'm trying desperately to find as much technical detail I can about the output of flashes such as Speedlights. Information such as the watts and wavelength data would be ideal.

Anyone know a source I could go to for this info? Greatly appreciated.
 
I'm sorry, I don't know where you can find this information but I am intrigued to know why you want it?
 
Trying to do a small science experiment with light but I can't find any info on the wavelengths of Speedlights. I would have thought Nikon or Canon or any of these others would put this info out there somewhere. Surely?
 
Speedlights are usually xenon based & will usually have a coating to reduce the UV output. wavelengths before the UV reduction would be similar to this https://en.wikipedia.org/wiki/File:Xenon_arc_lamp_profile.png

Light output can be measured with a flash meter (some of which are available quite cheaply)
I suspect your best bet for exploring light output a light will be to take meter readings through carefully chosen filters.

I have a high specification (~£15000) spectrometer at work but even with that I can't determine the spectral power distribution of light sources
I have used if for both filters & lenses to get an idea of transmission in the regions just outside the visible. (It works brilliantly for filters but not so well for wide angle lenses)
Most people aren't so lucky but there is an old Kodak Wratten filter book on archive.org, which has spectral data for their range of filters see https://archive.org/details/WrattenLightFilters :)
 
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Really interesting. Thanks for the details Petrochemist. I'm still amazed how this type of info is not readily available.
 
I'm trying desperately to find as much technical detail I can about the output of flashes such as Speedlights. Information such as the watts and wavelength data would be ideal.

Anyone know a source I could go to for this info? Greatly appreciated.

Speedlite manufacturers publish colour temperature info in Kelvins only, and power output is expressed as a Guide Number. Watt-seconds are never published for speedlights but if you assume a top-end model like the Canon 600EX-RT has something like 100Ws equivalent, you'd be pretty close. Bear in mind that Ws is a measure of energy stored in the capacitors and is only an appoximate guide to how much light is actually emitted.

For detailed colour spectrum data, you need a Sekonic C-700 spectrometer (about £1400) https://www.sekonic.com/portals/0/products/c700 12 pages brochure.pdf Google around for reviews and examples with flash that might provide the info you need, though if it helps pretty much all electronic flash puts out a full colour spectrum that is virtually a carbon copy of noon daylight at 5500K. That's at full power and at lower power settings, colour can shift slightly to cool or warm depending on the type of output control used. Mike Weeks has a C-700 and may be able to help more directly if you post in the Lighting section here.

The other critical factor is flash durations, measured with an oscilloscope or a Sekonic L-858 flash meter https://www.sekonic.com/united-states/products/l-858d-u/overview.aspx I have a lot of oscilloscope data - what exactly do you need? I think Mike also has a Sekonic L-858.

Suggest you repost in the Lighting forum. The more information on what you want to know and perhaps a bit more on your experiment would be helpful. There are any number of possible pitfalls and making what might appear to be completely logical assumptions could lead you seriously astray :)
 
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@HoppyUK knows more about this than me.. but there is one other factor which might be relevant in your case.

Colour temperature varies with power level. Indeed, some (all?) conventional flashes have different colour temperatures at different points during a single flash pulse. IGBT speedlites may be different again...
 
As above, I’m far from an expert, but IIRC for traditional power controlled flash units, they get warmer at lower power settings (but vary quite a lot) and IGBT units are more stable but get warmer at high power settings.

But Garry, Mike and Richard know much more about this kind of thing.

As an aside, I think that performance changes with age, so I’m not at all surprised you can’t get this level of detail from the manufacturers,
 
It would be remiss if colour temperature changes hadn't already been mentioned ;) :D

But what's missing from this thread now is more info from the OP. There are a lot of variables that are not obvious from headline data that could potentially skew any kind of scientific experiment. It's pretty much all out there if you know where to look but the detailed stuff is not generally available from the flash manufacturers as it's not relevant to intended use.
 
It would be remiss if colour temperature changes hadn't already been mentioned ;) :D

But what's missing from this thread now is more info from the OP. There are a lot of variables that are not obvious from headline data that could potentially skew any kind of scientific experiment. It's pretty much all out there if you know where to look but the detailed stuff is not generally available from the flash manufacturers as it's not relevant to intended use.


this is the same OP that had some fantastic piece of kit or training whose idea was panned if I am not mistaken

Mike
 
this is the same OP that had some fantastic piece of kit or training whose idea was panned if I am not mistaken

Mike

oh, the market research question about the light modifier that we removed when someone finally realised it was against the forum rules to run market research without speaking to the management first and decided to RTM it rather than just take the p***... :)
 
@HoppyUK knows more about this than me.. but there is one other factor which might be relevant in your case.

Colour temperature varies with power level. Indeed, some (all?) conventional flashes have different colour temperatures at different points during a single flash pulse. IGBT speedlites may be different again...
IGBT (both speedlights and studio flash) produces different colour temperature EFFECTS because, regardless of the power setting, it always fires at full power.
When it is set to a power setting that is less than full, the flash is quenched (switched off early) and the colour temperature effect of this is that the warm tail end of the flash isn't there, typically causing the light to become increasingly blue as the power setting is reduced - but not always, because some manufacturers, e.g. Godox and Canon, reduce the voltage in line with the power setting, or alternatively provide the option to do so.
This prevents the colour shift towards blue
 
It would be remiss if colour temperature changes hadn't already been mentioned ;) :D

But what's missing from this thread now is more info from the OP. There are a lot of variables that are not obvious from headline data that could potentially skew any kind of scientific experiment. It's pretty much all out there if you know where to look but the detailed stuff is not generally available from the flash manufacturers as it's not relevant to intended use.

Thanks for all your replies. It's tough to add details to this as I lack the terminology to describe what I'm after. Since posting this thread I have discovered that from flash to flash the difference is negligible but what matters most is what flashbulb is being used (In most cases Xenon). I'm basically trying to see how different filters applied to a flash may affect the quality of light being produced.
 
Thanks for all your replies. It's tough to add details to this as I lack the terminology to describe what I'm after. Since posting this thread I have discovered that from flash to flash the difference is negligible but what matters most is what flashbulb is being used (In most cases Xenon). I'm basically trying to see how different filters applied to a flash may affect the quality of light being produced.

Filters filter light, ie they remove something, usually a colour. If you start with a full colour spectrum, ie all flash, you can make it any colour you like by removing everything else.
 
Filters filter light, ie they remove something, usually a colour. If you start with a full colour spectrum, ie all flash, you can make it any colour you like by removing everything else.
This^

If you want to seriously produce specs on what a filter system actually outputs, you’ll need to measure it yourself. But it’s an answer to a questionable problem.

Because there’s a as much variation between a new and 10 year old flash as there is between 2 different makes. There’s a significant variation between a full power and lowest power flash on the same device.

So you can guarantee what your filter ‘filters’ but you can’t guarantee what’s left. It’s a moving feast. And what’s more, it’s irrelevant to 99.999% of all flash users. For the 0.001% who need the detail, they’ll have already invested in a method to measure for themselves.

I can’t help feeling this is yet another answer to a non existent problem.
 
applied to a flash may affect the quality of light being produced

The ‘quality’ of light is usually a term used to describe the effect of a modifier*, softbox, brolly, window, cloud, beauty dish etc. rather than the colour per-se.

*the gradation from shadow to light, the intensity of the shadow etc. rather than the colour which is all a filter would achieve.
 
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